| Techniques to establish the authenticity and integrity of digital images are becoming increasingly essential for secure transacting. Ideally, the authentication algorithm should distinguish incidental integrity maintaining distortions such as lossy compression from malicious manipulations. This has motivated research into semi-fragile watermarking.; A novel watermarking algorithm is proposed in this thesis that is both robust to compression and self-authenticating. The proposed algorithm is a content-based, semi-fragile watermarking method that employs a public-key scheme for still image authentication and integrity verification. The use of dual domains in the proposed algorithm enables greater control over the robustness and fragility of the overall scheme to manipulations, and provides very good classification of intentional and incidental tampering.; In addition, the thesis provides theoretical analysis for the performance and the feasibility of the scheme. We also present experimental results to verify the theoretical observations and the comparison results for the proposed algorithm to four popular techniques. |
